Electronic module

ABSTRACT

The present invention relates to an electronic module. In particular, to an electronic module which includes one or more components embedded in an installation base. The electronic module can be a module like a circuit board, which includes several components, which are connected to each other electrically, through conducting structures manufactured in the module. The components can be passive components, microcircuits, semiconductor components, or other similar components. Components that are typically connected to a circuit board form one group of components. Another important group of components are components that are typically packaged for connection to a circuit board. The electronic modules to which the invention relates can, of course, also include other types of components.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation-in-part of U.S. application Ser.No. 12/603,324 filed Oct. 21, 2009, which was a continuation-in-part ofU.S. application Ser. No. 11/907,795, now U.S. Pat. No. 7,609,527 whichwas filed on Oct. 17, 2007, which was a continuation of U.S. applicationSer. No. 10/546,820, now U.S. Pat. No. 7,299,546 which was filed Aug.25, 2005, which was a National Stage Entry of PCT/FI2004/000101 whichwas filed on Feb. 25, 2004 which claims priority to FI20030292 which wasfiled on Feb. 26, 2003. All of the above mentioned applications andpatents are incorporated herein by reference in their entirety.

SUMMARY OF THE INVENTION

The present invention relates to an electronic module. In particular, toan electronic module which includes one or more components embedded inan installation base. The electronic module can be a module like acircuit board, which includes several components, which are connected toeach other electrically, through conducting structures manufactured inthe module. The components can be passive components, microcircuits,semiconductor components, or other similar components. Components thatare typically connected to a circuit board form one group of components.Another important group of components are components that are typicallypackaged for connection to a circuit board. The electronic modules towhich the invention relates can, of course, also include other types ofcomponents.

The installation base can be of a type similar to the bases that aregenerally used in the electronics industry as installation bases forelectrical components. The task of the base is to provide componentswith a mechanical attachment base and the necessary electricalconnections to both components that are on the base and those that areoutside the base. The installation base can be a circuit board, in whichcase the construction and method to which the invention relates areclosely related to the manufacturing technology of circuit boards. Theinstallation base may also be some other base, for example, a base usedin the packaging of a component or components, or a base for an entirefunctional module.

The manufacturing techniques used for circuit boards differ from thoseused for microcircuits in, among other things, the fact that theinstallation base in microcircuit manufacturing techniques, i.e. thesubstrate, is of a semiconductor material, whereas the base material ofan installation base for circuit boards is some form of insulatingmaterial. The manufacturing techniques for microcircuits are alsotypically considerably more expensive that the manufacturing techniquesfor circuit boards.

The constructions and manufacturing techniques for the cases andpackages of components, and particularly semiconductor components differfrom the construction and manufacture of circuit boards, in thatcomponent packaging is primarily intended to form a casing around thecomponent, which will protect the component mechanically and facilitatethe handling of the component. On the surface of the component, thereare connector parts, typically protrusions, which allow the packagedcomponent to be easily set in the correct position on the circuit boardand the desired connections to be made to it. In addition, inside thecomponent case, there are conductors, which connect the connector partsoutside the case to connection zones on the surface of the actualcomponent, and through which the component can be connected as desiredto its surroundings.

However, component cases manufactured using conventional technologydemand a considerable amount of space. As electronic devices have grownsmaller, there has been a trend to eliminate component cases, which takeup space, are not essential, and create unnecessary costs. Variousconstructions and methods have been developed to solve this problem.

One known solution is flip-chip (FC) technology, in which non-packagedsemiconductor components are installed and connected directly to thesurface of the circuit board. However, flip-chip technology has manyweaknesses and difficulties. For example, the reliability of theconnections can be a problem, especially in applications, in whichmechanical stresses arise between the circuit board and thesemiconductor component. In an attempts to avoid mechanical stresses, asuitable elastic underfill, which equalizes mechanical stresses, isadded between the semiconductor component and the circuit board. Thisprocedural stage slows down the manufacturing process and increasescosts. Even the thermal expansion caused by the normal operation of adevice may cause mechanical stresses large enough to compromise thelong-term reliability of an FC structure.

U.S. Pat. No. 4,246,595 discloses one solution, in which recesses areformed in the installation base for the components. The bottoms of therecesses are bordered by an insulation layer, in which holes are madefor the connections of the component. After this, the components areembedded in the recesses with their connection zones facing the bottomof the recess, electrical contacts being formed to the componentsthrough the holes in the insulation layer. In such a method, problemscan arise, for instance, when aligning the feed-throughs with thecontact zones of the component. This is because the feed-throughs mustbe aligned relative to components lying under the insulation layer. Inother ways too, the method does not correspond to the technology usednowadays (the patent dates from 1981).

JP application publication 2001-53 447 discloses a second solution, inwhich a recess is made for the component in the installation base. Thecomponent is placed in the recess, with the component's contact zonesfacing towards the surface of the installation base. Next, an insulationlayer is made on the surface of the installation base and over thecomponent. Contact openings for the component are made in the insulationlayer and electrical contacts are made to the component, through thecontact openings. In this method too, the alignment of the feed-throughswith the contact zones of the component can cause problems, as thealignment must be made relative to a component lying under theinsulation layer. In the method, considerable accuracy is demanded inmanufacturing the recess and setting the component in the recess, sothat the component will be correctly positioned, to ensure the successof the feed-throughs, relative to the width and thickness of theinstallation board.

In general too, the connection of components through feed-throughs madein the insulation layer creates a challenge to techniques, in which anattempt is made to embed components inside a circuit board or otherinstallation base. Problems can arise, for example, due to the alignmentprecision, the stress created on the surface of the component by themanufacture of the hole, and by the covering of the edge areas of thefeed-through by conductive material. Even a partial reduction of theproblems relating to feed-throughs would be beneficial to the low-costmanufacture of reliable electronic modules that include unpackagedcomponents embedded in an installation base. On the other hand,embedding a component inside an installation base will allow theconstruction to better withstand mechanical stress, which has been aproblem in flip-chip technology.

The invention is intended to create a method, with the aid of whichunpackaged components, such as semiconductor components and particularlymicrocircuits, can be attached and connected reliably and economicallyto their installation base.

The invention is based on using an installation base, which includes alayer of insulating material and a conductor layer on the surface of thelayer of insulating material. The conductor layer also covers theinstallation cavity of the component. The component is placed in theinstallation cavity in such a way that the contact zones face towardsthe conductor layer, electrical contacts then being formed between thecontact zones of the component and the conductor layer. After this,conductor patterns are formed from the conductor layer, to which thecomponent is connected. In the method, both the components and theconductive patterns are aligned relative to the installation base, sothat they are also aligned relative to each other. At least onealignment mark for the alignment is made in the installation base.

More specifically, the method according to the invention ischaracterized by what is stated in claim 1.

Considerable advantages are gained with the aid of the invention. Thisbecause it is possible, with the aid of the invention, to embedunpackaged components in an installation base, reliably andeconomically.

Because the components can be embedded inside the installation base, inpreferred embodiments it is possible to achieve a reliable andmechanically durable construction.

With the aid of the invention, it is also possible to reduce the numberof the problems that appear in the prior art, which are caused by thefeed-throughs relating to connecting the components. This is because theinvention has embodiments, in which there is no need at all to makefeed-throughs, the components being instead connected, already in theinstallation stage, to the conductor membrane, from which the conductorsleading to the components of the electronic module are made.

In the embodiments, the components, of which there may be one orseveral, are installed on their installation base, such as a circuitboard, during the manufacture of the base, so that the base structure,is as it were, manufactured around the component. The components becomeembedded and attached as desired to this base structure.

In the embodiments of the invention, it is thus possible to manufacturea circuit board, inside which components are embedded. The inventionalso has embodiments, with the aid of which a small and reliablecomponent package can be manufactured around a component, as part of thecircuit board. In such embodiments, the manufacturing process is simplerand cheaper that manufacturing methods in which separate casedcomponents are installed and connected to the surface of the circuitboard. The manufacturing method can also be applied to use the method tomanufacture Reel-to-Reel products. Thin and cheap circuit-board productscontaining components can be made by using the methods according to thepreferred embodiments.

The invention also permits many other preferred embodiments, which canbe used to obtain significant additional advantages. With the aid ofsuch embodiments, a component's packaging stage, the circuit board'smanufacturing stage, and the assembly and connecting stage of thecomponents, for example, can be combined to form a single totality. Thecombination of the separate process stages brings significant logisticaladvantages and permits the manufacture of small and reliable electronicmodules. A further additional advantage is that such anelectronic-module manufacturing method can mostly utilize knowncircuit-board manufacturing and assembly technologies.

The composite process according to the embodiment referred to above is,as a totality, simpler that manufacturing a circuit board and attachinga component to the circuit board using, for example, the flip-chiptechnique. By using such preferred embodiments, the following advantagesare obtained, compared to other manufacturing methods:

-   -   Soldering is not needed in the connections of the components,        instead an electrical connection between the connection zones on        the surface of the component and the metal membrane of the        installation base is created, for example, by ultrasonic        welding, thermo-compression, or some other such method, in which        the temperatures required to achieve electrical connections,        though high, are of short duration and local, and in which high        temperatures are not required over a wide area. This means that        the connection of a component does not need metal being        maintained molten for a long time with its associated high        temperature. Thus, the construction is made more reliable than        soldered connections. Particularly in small connections, the        brittleness of the metal alloys create large problems. In a        solderless solution according to a preferred embodiment, it is        possible to achieve clearly smaller constructions than in        soldered solutions. The manufacturing method can even be        designed so that, during the connection process of a component,        heat is brought only to the area of the connection, so that the        areas most strongly heated are the connection zone of the        component and the area to which the component is connected.        Elsewhere in the structure the temperature remains low. This        gives greater freedom of choice when selecting the materials of        the installation base and the components. If ultrasonic welding        is used as the connection method, higher temperatures may only        be required to harden the fillers used. Polymer membranes, which        are hardened other than through the effect of heat, for example,        chemically or with the aid of electromagnetic radiation, such as        UV light, can also be used in the method. In such a preferred        embodiment of the invention, the temperature of the installation        base and components can be kept very low during the entire        process, for example, at less than 100° C.    -   As smaller structures can be manufactured using the method, the        components can be placed closer together. Thus, the conductors        between the components also become shorter and the        characteristics of the electronic circuits improve. For example,        losses, interferences, and transit-time delays can be        significantly reduced.    -   The method permits a lead-free manufacturing process, which is        environmentally friendly.    -   When using a solderless manufacturing process, fewer undesirable        intermetallics also arise, thus improving the long-term        reliability of the construction.    -   The method also permits three-dimensional structures to be        manufactured, as the installation bases and the components        embedded in them can be stacked on top of each other.

The invention also permits other preferred embodiments. For instance,flexible circuit boards can be used in connection with the invention.Further, in embodiments, in which the temperature of the installationbase can be kept low during the entire process, organic manufacturingmaterials can be used comprehensively.

With the aid of embodiments, it is also possible to manufactureextremely thin structures, in which, despite the thinness of thestructure, the components are entirely protected inside theirinstallation base, such as a circuit board.

In embodiments, in which the components are located entirely inside theinstallation base, the connections between the circuit board and thecomponents will be mechanically durable and reliable.

The embodiments also permit the design of electronic-modulemanufacturing processes requiring relatively few process stages.Embodiments with fewer process stages correspondingly also require fewerprocess devices and various manufacturing methods. With the aid of suchembodiments, it is also possible in many cases to cut manufacturingcosts compared to more complicated processes.

The number of conductive-pattern layers of the electronic module canalso be chosen according to the embodiment. For example, there can beone or two conductive-pattern layers. Additional conductive-patternlayers can be manufactured on top of these, in the manner known in thecircuit-board industry. A total module can thus incorporate, forexample, three, four, or five conductive-pattern layers. The verysimplest embodiments have only one conductive-pattern layer and indeedone conductor layer. In some embodiments, each of the conductor layerscontained in the electronic module can be exploited when formingconductive patterns.

In embodiments, in which the conductor layer connected to a component ispatterned only after the connection of the component, the conductorlayer can include conductor patterns even at the location of thecomponent. A corresponding advantage can also be achieved inembodiments, in which the electronic module is equipped with a secondconductive-pattern layer, which is located on the opposite surface ofthe base material of the module (on the opposite surface of theinsulation material layer relative to the conductive-pattern layerconnected to the component). The second conductor layer can thus alsoinclude conductive patterns at the location of the component. Theplacing of conductive patterns in the conductor layers at the locationof the component will permit a more efficient use of space in the moduleand a denser structure.

In the following, the invention is examined with the aid of examples andwith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 show a series of cross-sections of some examples ofmanufacturing methods according to the invention and schematiccross-sectional diagrams of some electronic modules according to theinvention.

FIG. 9 shows a cross-sectional view of an electronic module according tothe invention, which includes several installation bases on top of eachother.

FIGS. 10-12 show a series of cross-sections of some examples ofmanufacturing methods according to the invention and schematiccross-sectional views of an electronic module according to the inventionwherein a flexible sheet is provided as an installation base.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the methods of the examples, manufacturing starts from aninstallation base 1 of an insulating substance, which is thicker thanthe components 6 that are later to be connected to the base. Of course,the method can also be applied in such a way that the installation base1 and the component 6 are equally thick. In some embodiments, it is alsopossible to use components 6 that are thicker than the installation base1. Using a suitable method, through-cavities 2, selected to suit thesize of the components 6 to be installed, are made in the insulatingmaterial layer 1. The alignment of the components 6 also requiressuitable alignment marks, to creation of which several different methodsare available. One possible method is to make small through-holes 3 nearto the installation cavities 2 of the components 6. The precisealignment of the component preferably requires at least twothrough-holes. An unpatterned metal film 4, which acts as the conductingsurface of the installation base for the components 6 to be installedand connected, is made on the first surface 1 a of the insulatingsubstance layer 1. The metal film 4 can be manufactured, for example, bylaminating copper (Cu). The metal film 4 can also be a surfaced metalfilm, or some other film including several layers or several materials.In some embodiments, for example, a copper film surfaced with a layer oftin or gold can be used. In these embodiments, the surfacing istypically made on the side of the insulating material layer 1. Anotherpossible procedure is for the metal film 4 to include surfacing only inthe area of the installation cavities 2.

The components 6 are aligned with their installation cavities 2 with theaid of the alignment holes 3, or some other alignment marks and theconnection zones or contact protrusions 7 on the surface of thecomponents 6 are connected to the metal film 4. The connecting can takeplace, for example, using the ultrasonic or thermo-compression methods.

The ultrasonic method then refers to a method, in which two piecescontaining metal are pressed against each other while vibration energyat an ultrasound frequency is brought to the area of the joint. Due tothe effect of the ultrasound and the pressure created between thesurfaces to be joined, the pieces to be joined are bondedmetallurgically. Methods and equipment for ultrasonic bonding arecommercially available. Ultrasonic bonding has the advantage that a hightemperature is not required to form a bond.

The terms metal layer, metal film, metal contact bump, metal contactzone, and in general a metal item, refer to the fact that themanufacturing material of the item contains enough of at least one metalfor the item to form a metallurgical bond with another item. The itemcan naturally also include several metals as layers, accumulations,zones, or metal alloys. Possible metals include particularly copper,aluminium, gold, and tin.

The term thermo-compression method refers in turn to a method, in whichtwo pieces containing metal are pressed against each other while thermalenergy is brought to the area of the joint. The effect of the thermalenergy and the pressure created between the surfaces to be joined causethe pieces to be joined to be bonded metallurgically. Methods andequipment for thermo-compression bonding are also commerciallyavailable.

In some embodiments, contact bumps 5, to which the connection zones orcontact protrusions 7 of the components 6 are connected, are made on topof the conductive film 4. In such a method, the contact bumps 5 can alsobe used to align the components 6 during the components' installationstage. The components 6 can, of course, be aligned with the aid of otheralignment marks, for example, the alignment holes 3, if such are made inthe process being used. In embodiments using contact bumps 5, theprocedure can otherwise correspond to embodiments in which contact bumps5 are not used. The use of contact bumps 5 is justified, for example, ifthe material of the components' 6 contact zones or contact protrusions 7is not directly suitable for connection to the selected material of theconducting layer 4. In that case, the material of the contact bumps 5 isselected to permit a bond using the bumps 5 to be created. In suchembodiments, the contact bumps 5 are thus intended to match twodifferent conductor materials to each other. For this purpose, thecontact bump 5 can also be manufactured as a layered structure,containing two or more layers of possibly differing materials.

After the connection of the components 6, the space remaining in theinstallation cavity 2 around the component 6 is filled with a suitablefiller 8, usually some kind of polymer filler. The filling is intendedto secure the component 6 mechanically to the insulating material layer1, thus achieving a mechanically more durable construction. The fillermaterial 8 also supports the conductive patterns 14 to be formed laterfrom the conducting layer 4 and protects the component and the bondbetween the component 6 and the conducting layer 4 during the formationof the conductive patterns 14. In principle, the securing of thecomponent 6 is not, however, an essential operation, especially inembodiments, in which mechanical durability or a long life are notdemanded of the structure.

If desired, a conductive film 9, from which conductive patterns 19 canbe formed later, can also be made on the second surface 1 b of theinsulating material layer 1. The conductive film 9 can be manufacturedin a manner corresponding to that of the conductive film 4 made of thefirst surface 1 a of the base. The manufacture of a second conductivefilm 9 is not, however, necessary in simple embodiments and whenmanufacturing simple electronic modules. A second conductive film 9 can,however, be exploited in many ways, such as additional space forconductive patterns and to protect the components 6 and the entiremodule against electromagnetic radiation (EMC shielding). With the aidof a second conductive film 9 the structure can be reinforced andwarping of the installation base, for example, can be reduced.

The manufacturing processes according to the examples can be implementedusing manufacturing methods, which are generally known to those versedin the art of manufacturing circuit boards.

In the following, the stages of the method shown in FIGS. 1-8 areexamined in greater detail.

Stage A (FIG. 1):

In stage A, a suitable sheet 1 of insulating-material board, from whichthe body of the installation base is formed, is selected for themanufacturing process of the electronic module. The insulating-materiallayer 1 should preferably be thicker than the component to be installed.The component can then be embedded entirely inside the installation basewhile the electronic module will be even on both surfaces. Of course,thicker special components can also be embedded into the installationbase, their rear surface protruding outside the second surface 1 b ofthe insulating-material layer 1. This can be done particularly if it isnot intended to stack a second electronic module on top of theelectronic module being manufactured. In terms of the durability of theconstruction, however, it would be preferable for the components to beembedded entirely inside the installation base.

The insulating-material layer 1 can be, for example, a polymer base,such as a glass-fibre reinforced epoxy sheet FR4. In embodiments inwhich high temperatures are not needed in the manufacturing process, theinstallation base 1 can also be a cheap and flexible organic sheet.Other examples of suitable materials for the insulating-material layer 1are PI (polyimide), FR5, aramide, polytetrafluoroethylene, Teflon®, andLCP (liquid crystal polymer).

Stage B (FIG. 2):

In stage B, through-cavities 2 of a suitable size and shape for thecomponents to be embedded in the sheet are made in theinsulating-material layer 1. The cavities 2 can be made suitably, forexample, using some known method used in circuit-board manufacture. Thecavities 2 can be made, for example, mechanically by milling, impact,drilling, or with the aid of a laser. The cavities 2 extend through theentire insulating-material layer 1, from its first surface 1 a to itssecond surface 1 b. If several of the cavities 2 are made, they arepositioned relative to each other within the highest limits of accuracypossible for the manufacturing method being used.

Stage C (FIGS. 3A and 3B):

The example series of figures shows two alternative stage Cs. Accordingto a modification of the example process A (FIG. 3A), in stage C a thinconductive film 4, or more generally a conducting layer 4 is attached tothe second surface 1 b of the insulating-material layer 1. Theconductive film 4 is typically a metal film 4. In several embodiments, asuitable metal film is a copper (Cu) film, though other metals and alsometal alloys can very well be used. The copper film can be attached tothe insulating-material layer 1, for example, by lamination. An adhesivelayer, which is spread on the surface of the insulating-material layer 1or of the conductive film 4 prior to laminating the conductive film 4,can be used to aid the attachment of the conductive film 4. In theexample processes, patterns have not yet been made in the conductivefilm 4 at this stage, so that there is no need to particularly align thefilm 4 relative to the insulating-material layer 1. During, or after theattaching of the conductive film 4, through-holes 3, which can be usedlater to align the components in the component installation stage, canalso be made in the installation base. However, it is not essential tomake through-holes 3, as instead other suitable alignment marks can beused to align the components. If through-holes 3 are made, it would bebest for there to be at least two of them in the installation base. Itis also possible to proceed so that two through-holes 3 are made foreach component to be installed. In the embodiment shown in the figures,the through-holes 3 used to align the components extend through both theinsulating-material layer 1 and the conductive film 4. This has theadvantage that the same alignment marks (the through-holes 3) can beused for alignment on both sides of the installation base.

In stage C of the B modification of the example process (FIG. 3B), theprocedure is mainly the same as is the A modification, except that, inaddition to the stages shown in the A modification, in the Bmodification contact bumps 5 are made on the surface of the conductivefilm 4. The contact bumps 5 can be made in the conductive film 4 priorto the attachment of the conductive film 4 to the insulating materiallayer 1. The contact bumps 5 are then aligned relative to each other,while in the attachment stage of the conductive film 4 the conductivefilm 4, together with the contact bumps, is aligned relative to theinsulating-material layer 1 and particularly to the installationcavities 2 made in the insulating-material layer 1. A second alternativeis to first attach the conductive film 4 to the insulating-materiallayer 1 and after this make the contact bumps 5 on the bottom of theinstallation cavities 2. The contact bumps 5 are intended to connect acomponent to be installed later to the conductive film 4. In the exampleprocess, the contact bumps 5 are manufactured from some metallurgicallycompatible material, such as gold (Au). The contact bumps can be madeusing some process generally known in the circuit-board industry. Ifthrough-holes 3 are used in the process for alignment, they can be madein the same stage. The through-holes 3 can also be made after making thecontact bumps 5, in which case they should be aligned as accurately aspossible relative to the contact bumps 5, or else prior to manufacturingthe contact bumps 5, in which case the contact bumps 5 are alignedrelative to the through-holes 3.

Stage D (FIGS. 4A, 4B, and 4C):

Three modifications of Stage D are shown. In the A modification (FIG.4A), a component 6, which includes contact bumps 7 in the connectionzones of the component, is connected to the installation base. Thecontact bumps 7 of the component are connected to the conductive layer4, so that an electrical contact is formed between the contact bump 7and the conductive layer 4. It would be good for the connection to alsowithstand mechanical stress, so that the connection will not be easilybroken in later process stages, or during the operation of theelectronic module. The connection is formed using a suitable connectionmethod, for example, the ultrasonic and thermo-compression methods. Inthe connection stage, the through-holes 3 made for alignment, or otheravailable alignment marks are used to align the component 6.

In the B modification (FIG. 4B) too, a component 6, which includescontact bumps 7 in the connection zones of the component, is connectedto the installation base. The difference to the A modification is that,in the B modification, contact bumps 5 are also formed on top of theconductive layer 4. The contact bumps 7 of the component are thenconnected to the contact bumps 5 of the installation base. Theconnection can, as in modification A, be formed using a suitableconnection method, for example, the ultrasonic or thermo-compressionmethods. In the B modification, the component can be aligned, accordingto the embodiment, using the contact bumps 5, the through-holes 3, orother alignment marks suitable for alignment.

In the C modification of the example process, as in the B modification,an installation base is used, in which contact bumps 5 are made on topof the conductor layer 4. Unlike in the A and B modifications, in the Cmodification a component 6 is used, the surface of which has flatcontact zones, but no actual contact bumps 7, or other correspondingcontact protrusions. In the C modification, connection and alignment arecarried out as in the B modification, except that the connection isformed between the conductive material of the contact zones and thecontact bumps 5 of the installation base.

Stage E (FIGS. 5A, 5B, and 5C):

In stage E, the space remaining between the component 6 and theinstallation base is completely filled with a filler 8, which is, forexample, some suitable polymer. For example, epoxy filled with suitableparticles can be used as the polymer. The polymer can be spread using,for example, some known vacuum-paste-pressing device suitable for thetask. FIGS. 5A, 5B, and 5C show the installation base after theattachment of a component, in A, B, and correspondingly C modificationsof the process. The purpose of the filler 8 is to secure the component 6mechanically to the insulating-material layer 1, so that the electronicmodule will better withstand mechanical stress. In addition, the filler8 protects the component 6 during later process stages. Protecting thecomponent 6 can be particularly beneficial in embodiments, in whichconductive patterns are formed by etching the conductive layer 4 and inwhich the surface of the component 6 is sensitive to the effect of theetching agent used. Otherwise, the filling of the installation cavity 2is in no way essential and, at least in some embodiments, stage E can beomitted or performed at a later stage in the process.

In some embodiments, the installation cavity 2 can be dimensioned to thesize of the component 6, so that a friction fit is created between thecomponent and the installation cavity 2, filler 8 then not beingnecessarily required. Such an embodiment is, however more challenging interms of the manufacturing technology while the final result remainsmechanically weaker than in the embodiments shown in FIGS. 5A, 5B, and5C.

In embodiments, in which conductive patterns are formed on the secondsurface 1 b of the insulating layer 1, the manufacture of the conductivepatterns can be facilitated by evening the second surface 1 b of theinsulating layer 1, with the aid of a filler 8.

Stage F (FIGS. 6A, 6B, and 6C):

FIGS. 6A, 6B, and 6C show the electronic module after the carrying outof stage F, in modifications A, B, and C of the process, respectively.Stage F itself is, however, performed in the same way in each of thesemodifications. In stage F, conductive patterns 14 are formed from theconductive layer 4 using some suitable method. The conductive patterns14 can be made, for instance, by removing the conductive material of theconductive layer 4 from outside of the conductive patterns. Theconductive material can be removed, for example, using one of theselective etching methods that are widely used and well known in thecircuit-board industry. If the conductive layer 4 is made from a specialmaterial, the conductive patterns 14 can also formed in such a way thatthe conductivity of the conductive material 4 is removed from outside ofthe conductive patterns, for example, with the aid of electromagneticradiation. When using a conversely reactive material, the material isput into a conductive state in the area of the conductive patterns.Thus, the conductive layer 4 is, in the previous stages of the method,actually the insulating layer, which can be converted to be conductivewith the aid of special treatment. The manner of forming the conductivepatterns 14 is thus not, as such, essential to the manufacture of theelectronic module.

The conductive patterns are aligned with the aid of alignment marks madein the installation base. The alignment marks can be the same that areused to align the components, or else separate alignment marks, whichare made at a specific location relative to the alignment marks used inthe alignment of the components. Because the components and conductivepatterns are both aligned relative to the alignment marks on theinstallation base, they are thus also aligned relative to each other.

If through-holes 3 are made in the embodiment, the conductive patternsto be made can be aligned with the aid of the through-holes 3.

After stage F, the electronic module includes a component 6, or severalcomponents 6 and conductive patterns 14, with the aid of which thecomponent or components 6 can be connected to an external circuit, or toeach other. The conditions for manufacturing a functional totality thenexist already. The process can thus be designed in such a way that theelectronic module is already finished after stage F and FIGS. 6A, 6B,and 6C show examples of some possible electronic modules that can bemanufactured using the example methods. Of course, if it is wished, theprocess can also continue after stage F, for example, by makingconductive patterns on the second surface 1 b of the insulating layer 1,or by surfacing the electronic module with a protective substance.

Stage G (FIGS. 7A, 7B, and 7C):

FIGS. 7A, 7B, and 7C show embodiments of the manufacturing process as A,B, and C modifications, in which, after stage E, a conductive layer 9 isformed on the second surface 1 b of the insulating layer 1. In theembodiments shown in FIGS. 7A, 7B, and 7C, stage F is thus omitted, themethod moving to stage G directly from stage E.

Stage G corresponds to stage C, in which a conductive layer 4 is made onthe first surface 1 a of the insulating layer 1. As in stage C, theconductive layer 9 can be made, for example, by laminating, on thesecond surface 1 b of the insulating layer 1, a type ofelectrically-conductive film 9 corresponding to the one on the firstsurface 1 a. The lamination can exploit an adhesive spread on thesurface of the base or film, and which during the lamination stageattaches the installation base and the electrically-conductive film toeach other.

Stage H (FIGS. 8A, 8B, and 8C):

Stage H can be carried out after stage G, if it is wished to pattern theconductive layer 9 formed on the second surface 1 b of the insulatinglayer 1. Stage H corresponds to stage F, with the difference that, instage H, in addition to the conductive patterns 14, other conductivepatterns 19 are formed from the conductive layer 9 made on the secondsurface 1 b of the insulating layer 1. After carrying out stage H, theelectronic module will include conductive patterns on both surfaces ofthe insulating-material layer 1. The second conductive-pattern layerwill provide more diverse connection possibilities between thecomponents 6. FIGS. 8A, 8B, and 8C show the electronic module after thecarrying out of stage H, respectively in A, B, and C modifications ofthe process. Stage F itself is, however, carried out in the same way ineach of these modifications.

After stage H, the electronic module includes a component 6, or severalcomponents 6 and conductive patterns 14 and 19. The examples of FIGS.8A, 8B, and 8C show some possible electronic modules that can bemanufactured using the example methods. If desired, the process cancontinue after stage H, for example, by making a feed-through, orfeed-throughs, with the aid of which suitable points in the conductivepattern 14 can be connected electrically to suitable parts of theconductive pattern 19. The electronic module can also be surfaced with aprotective substance.

FIG. 9

FIG. 9 shows a multi-layered electronic module, which includes threeinstallation bases 1 laminated on top of each other, together with theircomponents 6, and a total of six conductive-pattern layers 14 and 19.The installation bases 1 are attached to each other with the aid ofintermediate layers 32. The intermediate layer 32 can be, for example, apre-preg epoxy layer, which is laminated between the installation bases1. After this, holes running through the module are drilled in theelectronic module, in order to form contacts. The contacts are formedwith the aid of a conductive layer 31 grown in the holes. With the aidof the conducts 31 running through the electronic module, the variousconductive-pattern layers 14 and 19 of the installation bases 1 can besuitably connected to each other, thus forming a multi-layeredfunctioning totality.

On the basis of the example of FIG. 9, it is clear that the method canalso be used to manufacture many different kinds of three-dimensionalcircuit structures. The method can be used, for example, in such a waythat several memory circuits are placed on top of each other, thusforming a package containing several memory circuits, in which thememory circuits are connected to each other to form a single functionaltotality. Such packages can be termed three-dimensional multichipmodules. In modules of this kind, the chips can be selected freely andthe contacts between the various chips can be easily manufacturedaccording to the selected circuits.

The sub-modules (installation bases 1 with their components 6 andconductors 14 and 19) of a multi-layered electronic module can bemanufactured, for example, using one of the electronic-modulemanufacturing methods described above. Some of the sub-modules to beconnection to the layered construction can, of course, be quite aseasily manufactured using some other method suitable for the purpose.

The examples of FIGS. 1-9 show some possible processes, with the aid ofwhich our invention can be exploited. Our invention is not, however,restricted to only the processes disclosed above, but instead theinvention also encompasses various other processes and their endproducts, taking into account the full scope of the Claims and theinterpretation of their equivalences. The invention is also notrestricted to only the constructions and methods described by theexamples, instead it is obvious to one versed in the art that variousapplications of our invention can be used to manufacture a wide range ofdifferent electronic modules and circuit boards differing greatly fromthe examples described above. Thus, the components and wiring of thefigures are shown only with the intention of illustrating themanufacturing process. Thus, many alterations to and deviations from theprocesses of the examples shown above can be made, while neverthelessremaining within the basic idea according to the invention. Thealterations can relate, for example, to the manufacturing techniquesdescribed in the different stages, or to the mutual sequence of theprocess stages.

With the aid of the method, it is also possible to manufacture componentpackages for connection to a circuit board. Such packages can alsoinclude several components that are connected electrically to eachother.

The method can also be used to manufacture total electrical modules. Themodule can also be a circuit board, to the outer surface of whichcomponents can be attached, in the same way as to a conventional circuitboard.

FIG. 10 illustrates further embodiments of the present invention whereina flexible sheet 10 is provided as an installation base. Conductivepatterns 14 are further affixed to the flexible sheet. The conductivepatterns may be affixed to the flexible sheet such that the conductivepatterns may flex with the flexible sheet. The conductive patternsthemselves may be flexible. A component, for example a microchip, isconnected to the conductive patterns via flat contact elements 7. Thecomponent may be secured to the flexible sheet via a filler 11. Thefiller may be rigid. In certain embodiments the component may beentirely enclosed in the filler as illustrated in FIG. 10.

The filler may provide protection for the component. Further benefits ofthe filler could include providing structure to the electronic module.At the same time a rigid filler with a flexible sheet andconductive-pattern layer allows for varied configurations of theelectronic module as illustrated by FIGS. 11 and 12.

In the example embodiment illustrated by FIG. 11 two components 6 areenclosed in a filler 11. This filler may be applied to the componentsindividually prior to the electronic module being folded. As shown, theflexible sheet 10 and conducive patterns 14 could allow for theelectronic module of FIG. 10 to be folded upon itself to form theelectronic module of FIG. 11.

FIG. 11 further illustrates two components which are affixed to the sameside of the flexible sheet 10 and yet oriented differently. Orientationas illustrated in FIG. 11 refers to the direction the contact pads 7 arefacing. At least for some applications, this allows for simplermanufacture of a multi-layered structure by first manufacturing a singlelayer structure on a flexible or semi-flexible basis and thenmanipulating the structure to form a multi-layered structure withcomponents in at least two different layers.

FIG. 12 further illustrates an electronic module which could be formedfrom the electronic module of FIG. 10. Within FIG. 12 the components 6are affixed to the flexible sheet 10 via an affixing agent 12. Theconductive patterns 14 are also affixed to the flexible sheet andconnected to at least some of the flat contact zones 7 of thecomponents. Filler 10 is placed opposite the components between portionsof the flexible sheet. This could serve to provide electrical isolationbetween portions of the conductive patterns. The filler may also providestructure to the electronic module.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting. Reference throughout this specification to “oneembodiment” or “an embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of lengths, widths, shapes, etc., to provide a thoroughunderstanding of embodiments of the invention. One skilled in therelevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

1. An electronic module, comprising: a flexible sheet; a firstconductive-pattern layer on a surface of the flexible sheet; a componenthaving flat contact zones, at least some of the flat contact zones beingelectrically connected to the first conductive-pattern layer by means ofsolderless and metallurgical connections, said connections eachcomprising at least one solid contact bump between the firstconductive-pattern layer and the respective contact zone; and a filleraround the component, the filler securing the component mechanically tothe flexible sheet.
 2. The electronic module of claim 1, wherein thefiller is rigid.
 3. The electronic module of claim 1, wherein thecomponent is entirely surrounded by the filler.
 4. The electronic moduleof claim 1, wherein the first conductive-pattern layer is flexible. 5.The electronic module according to claim 1, wherein the firstconductive-pattern layer comprises: a layer of first conductive materialextending throughout the single conductive-pattern layer; and a surfacelayer provided on the layer of first conductive material present only inthe area of the component.
 6. The electronic module of claim 1,comprising a plurality of components electrically connected to the firstconductive-pattern layer.
 7. The electronic module of claim 6, whereinthe plurality of components are affixed to the same side of the flexiblesheet and arranged in at least two different orientations.
 8. Theelectronic module of claim 6, wherein the plurality of components areaffixed to the same side of the flexible sheet and arranged to form amulti-layered electronic module.
 9. The electronic module of claim 6,wherein the plurality of components are electrically connected to eachother by the first conductive-pattern layer.
 10. The electronic moduleof claim 1, wherein the flexible sheet is organic.
 11. The electronicmodule of claim 1, wherein said connections each comprise a first solidcontact bump and a second solid contact bump, the second solid contactbumps located on the surfaces of the respective contact zones and thefirst solid contact bumps connecting the respective second solid contactbumps to the first conductive-pattern layer.
 12. The electronic moduleof claim 11 wherein the metallurgically electrical connections arefacilitated by the presence of one or more metals selected from thegroup consisting of copper, aluminium, gold and tin.
 13. An electronicmodule, comprising: a first conductive-pattern layer having a firstsurface, a second conductive-pattern layer having a second surface, aflexible insulating-material layer between the first surface of thefirst conductive-pattern layer and the second surface of the secondconductive-pattern layer, a component having flat contact zones betweenthe first surface of the first conductive-pattern layer and the secondsurface of the second conductive-pattern layer, at least some of theflat contact zones being electrically connected to the firstconductive-pattern layer by means of solderless and metallurgicalconnections, said connections each comprising at least one solid contactbump between the first conductive-pattern layer and the respectivecontact zone, and a filler around the component, the filler securing thecomponent mechanically to the flexible sheet.
 14. The electronic moduleof claim 13, wherein said connections each comprise a first solidcontact bump and a second solid contact bump, the second solid contactbumps located on the surfaces of the respective contact zones and thefirst solid contact bumps connecting the respective second solid contactbumps to the first conductive-pattern layer.
 15. The electronic moduleof claim 14, wherein the first solid contact bumps include a layeredstructure, containing at least two layers of at least two differentmaterials.
 16. The electronic module of claim 14, wherein the secondsolid contact bumps include a layered structure, containing at least twolayers of at least two different materials.
 17. The electronic module ofclaim 14, wherein the component is a microcircuit.
 18. A multi-layeredelectronic module, comprising: a flexible sheet having a first flatportion and a second flat portion and a curved portion between the firstflat portion and the second flat portion; a first conductive-patternlayer on a surface of the flexible sheet and comprising at least oneconductor extending over the curved portion from the first flat portionto the second flat portion; a first component affixed to the first flatportion, the first component having flat contact zones, at least some ofthe flat contact zones being electrically connected to the firstconductive-pattern layer by means of solderless and metallurgicalconnections, said connections each comprising at least one solid contactbump between the first conductive-pattern layer and the respectivecontact zone; a second component affixed to the second flat portion, thefirst component having flat contact zones, at least some of the flatcontact zones being electrically connected to the firstconductive-pattern layer by means of solderless and metallurgicalconnections, said connections each comprising at least one solid contactbump between the first conductive-pattern layer and the respectivecontact zone; and a filler between the first flat portion and the secondflat portion.
 19. The multi-layered electronic module of claim 18,wherein the first component and the second component are located betweenthe first flat portion and the second flat portion.
 20. Themulti-layered electronic module of claim 18, wherein are the first flatportion and the second flat portion are located between the firstcomponent and the second component.